Lubricating composition containing a synergistic extreme pressure additive



Patented Jan. 19, 1960 2,921,902 LUBRICATING coivirosmoN CONTAINING A v SYNERGISTIC EXTREME PRESSURE ADDI- Harold J. Watson, Fishkil l, N.Y., assignor to Texaco Inc., a corporation of Delaware No Drawing. Application June 3, 1957 Serial No. 662,992

6 Claims. (Cl. 252-'33.6)

This invention relates to an improved lubricating composition containing a combination of additives which exhibits synergistic extreme pressure properties. More particularly, this invention relates to mineral oils containing a mixture of a chlorinated high molecular weight hydrocarbon and a metal dialkyl dithiocarbamate as an extreme pressure additive mixture.

The need for improved lubricating oils exhibiting extreme pressure properties increases continually as industrial machinery is subjected to increasingly heavier loads and as performance standards are raised higher. Recently, the need for lubricants possessing extreme pressure properties has arisen in connection with turbine oils employed in the lubrication of marine machinery. A recently issued military specification, MIL-Ll733lA(Ships), defines the desired properties of an extreme pressure turbine oil. The present invention defines an additive combination possessing synergistic extreme pressure action which is particularly useful in the formulation of marine extreme pressure turbine oils.

The synergistic extreme pressure additive combination of this invention consists essentiallyof a chlorinated paraffin wax and a metal dialkyl dithiocarbamate in a weight ratio of to 500 parts of chlorinated paraffin wax per part of metal dialkyl dithiocarbamate. The lubricating compositions of the invention comprise 0.5 to 5.0 weight percent chlorinated paraffin Wax and 0.002 to 0.1 weight percent metal dialkyl dithiocarbamate. Very. small concentrations of metal dialkyl dithiocarbamates, which have substantially no extreme pressure properties in themselves, cause a significant and substantial improvement in the extreme pressure properties of chlorinated paraffin wax.

With the addition of conventional anti-oxidant, antifoam, and anti-rust additives, extreme pressure turbine lubricants meeting the rigid requirements of MILL 17331A(Ships) were formulated using the synergistic extreme pressure additive combination of this invention.

The mineral lubricating base oil employed in the lubricant compositions of this invention may be derived from paraflin base, napthene base or mixed parafiin-naphthene base crudes. The viscosity range of the mineral lubricating base oil is between 80 and 1000 SUS at100 F. The v base oils usually have a flash point falling between 320 and 520 F., a pour point within the range of +20 to --50 F. and a viscosity index between 10 and 120.

Particularly preferred oils for marine turbine lubricants are paraffin base distillate oils which have been solvent refined, solvent dewaxed and clay percolated and which have an SUS at 100 F. between 300 and 600. A blend of .furfural refined, acidetreated, clay-contacted solvent dewaxed and clay percolated parafiin base distillate oils having an SUS at 100 F. of 500-510, a pour of l0 F., a flash above 350 F., and a viscosity index of about 90 has been widely used as a base oil for marine turbine oils. The chlorinated parafiin wax employed in the present lubricant is one having a high content of combined chlorine, the major proportion of which is in a so-called active state. The chlorine content of this additive is between 35 and 45 weight percent of the compound. For example, a preferred material of this character has a total combined chlorine content of about 40-45 percent with an active chlorine content of about 29-34 percent. Preferably, the chlorinated paratfin wax contains a small proportion of an oil-soluble corrosion inhibitor of the type disclosed in U.S. Patent No. 2,298,638, which functions to neutralize the effect of any decomposition of the chlorinated paraflin wax with the release of free chlorine.

. Phenoxy propylene oxide is used as a corrosion inhibitor of this type.

The concentration of the chlorinated paraflin wax in the lubricant composition of the invention falls between 0.5 and 5.0 weight percent of the total lubricant with concentrations between 1.0 and 2.5 weight percent usually being employed. It is significant that the desired level of extreme pressure activity is obtained With relatively low concentrations of chlorinated parafiin wax, which fact is directly attributable to the synergistic action of the metal dialkyl dithiocarbamate.

The metal dithiocarbamates which are employed as the second component of the additive combination of our invention are zinc and cadmium salts of organic-substituted dithiocarbamic acids having the general formula wherein R and R are aliphatic hydrocarbon radicals containing 2 to 14 carbon atoms and M is zinc or cadmium. Zinc dialkyl dithiocarbamates are particularly useful. Examples of suitable compounds are Zinc dibutyl dithiocarbamate, zinc diamyl dithiocarbamate, zinc di(2-ethylhexyl) dithiocarbamate, zinc octyl-butyl dithiocarbamate, cadmium propyl-octyl dithiocarbamate, zinc dioctyl dithiacarbamate, zinc dinonyl dithiocarbamates, cadmium dicetyl dithiocarbamate, cadmium dibutyl dithiocarbamate and cadmium diamyl dithiocarbamate.

Only small concentrations of zinc and cadmium dialkyl dithiocarbamates are necessary to exert their synergistic action on the extreme pressure properties of chlorinated parafiin wax. Concentrations as low at 0.002 to 0.1 weight percent metal dialkyl dithiocarbamate based on the total lubricating oil composition effect a substantial improvement in the extreme pressure properties of a lubricating oil containing 0.5 to 3.0 weight percent chlorinated paraffin Wax. The concentration of the metal dialkyl dithiocarbamate in'the finished commercial lubricants is usually between 0.008 and 0.05 weight percent.

The weight ratio of chlorinated paraflin wax to metal dialkyl dithiocarbamate in the synergistic extreme pressure additive of the invention expressed independently of the mineral lubricating oil is 5 to 500 and preferably 50 to 300 parts of chlorinated paraflin wax per part of metal dialkyl dithiocarbamate. This ratio indicates very clearly the effectiveness of metal dialkyl dithiocarbamates in synergistically raising the extreme pressure property of chlorinated paratfin Wax.

Alkyl-substituted phenols are usually incorporated in the lubricants of the invention as anti-oxidants. The preferred and most commonly used alkyl phenol antioxidant is 2,6-di-te1tiary butyl-4-met'nylphenol which is commercially available from a number of sources. Examples of other phenolic type anti-oxidants which may be employed are 2,6-di-tertiary butylphenol; 2,6-di-tertiary amyl-4-methylphenol; and 2,6-di-isopropyl-4-methylphenol. Hindered phenols of this type are employed in concentrations between 0.1 and 1.0 weight percent.

Although hindered phenol type anti-oxidants are the most widely used anti-oxidants in the lubricant composi are employed in the same concentrations as the hindered phenol anti-oxidant.

The anti-rust compounds which are particuluarly necessary for marine turbine lubricants are the alkyl-substituted aliphatic dicarboxylic acids such as alkenyl succinic acid, alkyl maleic acid and alkyl succinic acids. These aliphatic-substituted dicarboxylic acids are usually used in conjunction with a minor portion of an acid ester of an alkyl phosphate. A mixture of monoand dilauryl esters of phosphoric acid is widely used in conjunction with an aliphatic-substituted aliphaticdicar'bo-xylic acid as an anti-rust additive mixture. A detailed description of this additive mixture is found in US. Patent 2,452,321, which issued October 26, 1948, to J. A. Patterson and H. D. Kluge, and which is assigned to The Texas Company. The dicarboxylic acid is usually employed in a concentration between 0.01 and 0.1 weight percent and the alkyl acid phosphate in a concentration between 0.0001 and 0.03 weight percent.

Organic silicones are normally incorporated in the lubricants of the invention to impart anti-foam properties thereto. The silicones are usually of dialkyl or mixed alkyl-aryl silicone type. Dimethyl silicone is normally employed as the anti-foam agent. The silicone is incorporated in the lubricant by means of a kerosene concentrate containing 5 to 15 Weight percent silicone. A very satisfactory anti-foam agent is kerosene concentrate containing weight percent dimethyl silicone. The kerosene concentrate is employed in an amount of 0.005 to 0.025 weight percent which is sufficient to provide a silicone polymer concentration of 50 to 200 parts per million.

The synergistic extreme pressure properties of an additive mixture of chlorinated paraffin wax and zinc dialkyl dithiocarbamate Was demonstrated in a base oil comprising mineral lubricating oil; 0.3 weight percent,'2,6-di t-butyl-4-methylphenol; 0.033 weight percent of an antirust concentrate comprising 45 percent of a C alkenyl succinic acid in which the alkenyl group is propylene tetramer, 10 percent of a mixture of mono and dilauryl phosphoric acid esters and 45 percent diluent oil; and about 0.001 weight percent of an anti-foam concentrate comprising 10 weight percent dimethyl silicone in kerosene. The mineral lubricating oil was a furfural refined, acid-treated, clay-contacted, solvent dewaxed and clay percolated paraffin base distillate having an SUS viscosity at 100 F. of about 500, a pour of 10 F. maximum, a flash of 380 F. minimum and a viscosity index of about 90.

I In Table I, there are presented data proving the synergistic extreme pressure action of'a mixture of zinc dialkyl dithiocarbamate and chlorinated parafiin wax having a chlorine content of 40 weight percent.

The data in the foregoing table prove that mixtures of chlorinated paraflin wax and zinc or cadmium dibutyl dithiocarbamate' possess a surprising synergistic extreme pressure action. Although zinc butyl dithiocarbamate in a concentration of 0.01 percent-had no effect on the mean Hertz load of the base oil and chlorinated paraffin wax in a concentration of -2.0 weight percent raised the mean Hertz load from 17 to 26, an additive combination of 0.01 weight percent zinc dibutyl dithiocarbamate and 2.0 Weight percent'chlorinated paraifin wax gave a mean Hertz load of 31. It'is also significant that a mixture of weight percent zinc dibutyl dithiocarbamate gave a mean 2.0 weight percent chlorinated parafiin wax and 0.01 Hertz load equivalent to that obtainable with 3.0 weight percent chlorinated parafiin wax and that a mixture of 2.0 weight percent chlorinated paraflin wax and 0.05 weight percent zinc dibutyl dithiocarbamate gave a mean Hertz load of 35, whichis significantly higher than the 31 value obtained with 3.0 weight percent chlorinated paraflin Wax alone.

Employing the synergistic extreme pressure additive combination ofthis invention, there has been formulated a finished lubricant which qualifies against MILL- 17331A(Ships) formarine turbine lubricants containing extreme pressure properties; the composition of this product is shown in Table II.

Table II Lubricant composition 7 in Weight percent Base oil 97.656 2,6-di-t-butyl-4 methylpheno1 0.3 C alkenyl (propylene tetramer) succinic acid 0.03 35 Mixture of monoand dilauryl acid phosphates 0.003

Chlorinated paraflin wax 2.0 Zinc dibutyl dithiocarbamate 0.01

Anti-foam concentrate 0.001

The base oil in the above formulation is the same as that employed as the base oil for the data summarized in Table I. The chlorinated parafiin wax had a chlorine content of 40 weight percent.

In Table. III, there are shown the properties of this lubricant in comparison with the specifications of MILL17331A. V

Table III Tests MIL-L-l7331A Lubricant of Table II Flash, 000, F 350 min 485 Viscosity:

cs. at F.- 82- 0 109. 3

SUS at 100 F 506. 6

cs. at 210 F 8 9 min 10. 8

SUS at 210 F 62. 2 Pour, F--- 20 max 0 Corr. 0.8. 212 F. (ASTM) 1B EMAIL--- 1A Neutrality, Qual Pass Neut. No. (ASIM) 0.06 Emulsion, F.:.

Minufl 30 max 30, 30

cc, onfl '4 2,0 ASTM Foam, Seq. 1-2-3 300-25-300 max 0-0-0 Ryder Gear Test, 1b.,lin. 2,200 min 1 2,790 Mean Hertz Load, kg 25 min '31 Salt Water Rust'Test (with wash Pass ASIM Oxidation, hrs. to 2 NN Average of two.

Lubricant whose composition is shown in Table II has been evaluated as the turbine lubricant on the tanker Indiana for two months with excellent results.

Obviously, many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof and, therefore, only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A lubricating composition comprising a mineral lubricating oil as the major component, 0.5 to 5.0 weight percent chlorinated parafiin wax and 0.002 to 0.1 weight percent metal dialkyl dithiocarbamate in which said metal is selected from the group consisting of zinc and cadmium and said alkyl group contains 2 to 14 carbon atoms.

2. The lubricating composition of claim 1 containing 1.0 to 2.5 weight percent chlorinated paraflin wax and 0.008 to 0.05 weight percent metal dialkyl dithiocarbamate.

3. The lubricating composition of claim 1 in which said metal dialkyl dithiocarbamate is zine dialkyl dithiocarbamate.

4; The lubricating composition of claim 1 in which said metal dialkyl dithiocarbamate is zinc dibutyl dithiocarbamate.

5. The lubricating composition of claim 1 in which said metal dialkyl dithiocarbamate is dithiocarbamate.

cadmium dibutyl 6 6. A lubricating composition comprising a highly re- (fined paraflin base distillate oil having an SUS at 100 F. between 300 and 600 as the major component, 0.5 to 5.0 weight percent chlorinated paraffin wax, 0.002 to 1.0

weight percent metal dialkyl dithiocarbamate in which the metal is selected from the group consisting of zinc and cadmium and said alkyl group contains 2 to 14 carbon atoms, 0.1 to 1.0 Weight percent hindered phenol anti-oxidant, 0.01 to 1.0 weight percent alkenyl succinic acid, 0.0001 to 0.03 weight percent alkyl acid phosphate and to 200 p.p.m. of a silicone polymer.

References Cited in the file of this patent UNITED STATES PATENTS 2,394,536 Denison et al. Feb. 12, 1946 2,400,106 Denison et al. May 14, 1946 2,629,694 Woods et a1 Feb. 24, 1953 2,713,558 Schmitz July 19, 1955 2,726,209 Fainman Dec. 6, 1955 

1. A LUBRICATING COMPOSITION COMPRISING A MINERAL LUBRICATING OIL AS THE MAJOR COMPONENT, 0.5 TO 5.0 WEIGHT PERCENT CHLORINATED PARAFFIN WAX AND 0.002 TO 0.1 WEIGHT PERCENT METAL DIALKYL DITHIOCARBAMATE IN WHICH SAID METAL IS SELECTED FROM THE GROUP CONSISTING OF ZINC AND CADMIUM AND SAID ALKYL GROUP CONTAINS 2 TO 14 CARBON ATOMS. 